I am new and going to start my first session in a couple weeks - so I'm slowly starting to make my character. I started with more of my character's personality and role in the group than I did with the race and class and was hoping for some advice on finding those.

I see her as being the healer of the group, with origin of nature. Also, I see her as being very insightful and (ideally) perceptive. In battle, she sticks to the shadows. It would be awesome if she could make the trees attack the enemy, or attack them with ice or something.

So far I like the class Bard the best, but also still in consideration is: Paladin, Wizard, or Invoker.

As far as race goes, I'm really drawn to the creatures of the Feyworld - Elf, Eladrin, or Halfelf, but maybe a Gnome (a feyworld as well - I know, just I feel like in a different way than the others) or Deva would be better for my character.

Also, races and classes list which of the other (races->classes and visa versa) they go well with. How much should I listen to this, or is it really all suggestion?

It isn't clear which sources you have available beyond the PHB1 and PHB2, but...

The closest fit to what you've described is probably the shaman, although if you're willing to forego the healer aspect as a primary focus then the druid is also a viable option along with the wizard and invoker.

It would help to have some idea of what motivates this character along with the sort of things you want her to be able to do.

Primal classes like Shamans or Druids are definitely more along the line of what you're talking about in your description. Shamans have the best stats for getting all the skills you are looking for as well. As for races Shardmind is a perfect fit statwise but makes no sense lorewise. However, that can be a load of fun as well .

Bards are an extremely versatile leader class that has quite a few strong controller powers as well as some healing. In fact I would say they are the most versatile class period because of their ability to multiclass as many times as they want. There are lots of interesting things you can do with bards to fill almost any role many of which are in the optimization section.

Your character will do a lot of growing just over the course of the first few adventures so make sure as he/she is getting higher in level you make sure to develop his/her story more. For instance, my cleric started out as a generic cleric of pelor. During paragon he received an rare weapon that shared a psychic link with him. Over time, because the weapon was so powerful it began to try to take over his body so he would wear an eye patch to help contain the control of the sword. At the beginning of every adventure I would roll at d20 and if it was higher then 10 the sword would take control of my body and the he would become more willing to let things die. Little interesting add on lore to your character can make it that much more fun.

I understand your desire to play something that is connected to nature but in reality, that is mostly fluff. Consider whatever class you think is fun and tell the DM he used to live with wolves (I am sure you can be more creative). The "origin of nature" you speak of can be placed upon any race. PCs are interesting characters in a very interesting world. There are always exceptions to the rule so play what you would like and then weave in your story.

If you want your spell to shoot out of the tree, tell the DM that is what happened. It doesn't need to have in-game effects (cover and the like). If it makes you have more fun, the DM should be onboard.